Until now, compiler logs could only be created from MSBuild binary logs (.binlog). This adds a path to serialize an active Roslyn workspace into a .complog for later investigation.

New public API

// CompilerLogUtil
public static List<string> CreateFromWorkspace(
    Workspace workspace,
    string compilerLogFilePath,
    Func<Project, bool>? predicate = null,
    CancellationToken cancellationToken = default)

public static List<string> CreateFromWorkspace(
    Workspace workspace,
    Stream compilerLogStream,
    Func<Project, bool>? predicate = null,
    CancellationToken cancellationToken = default)

Usage:

using var solutionReader = SolutionReader.Create("build.complog");
var workspace = new AdhocWorkspace();
workspace.AddSolution(solutionReader.ReadSolutionInfo());

// Snapshot the current workspace state
var diagnostics = CompilerLogUtil.CreateFromWorkspace(workspace, "snapshot.complog");

Implementation

• CompilerLogBuilder.AddFromWorkspace(Project, CancellationToken) — new internal method that serializes a workspace Project:
  • Source, additional, and analyzer-config documents are written preserving original encoding
  • PortableExecutableReference with a FilePath → reads assembly from disk (same as binlog path)
  • CompilationReference (project-to-project) → emits the referenced compilation to memory and embeds the PE bytes
  • AnalyzerFileReference → reads from disk; other analyzer reference types produce a diagnostic and are skipped
• CompilerLogUtil.CreateFromWorkspace — iterates workspace.CurrentSolution.Projects, calls AddFromWorkspace per project, returns collected diagnostics

Limitations

When a workspace is loaded with BasicAnalyzerKind.InMemory (default on .NET), the in-memory analyzer references cannot be re-serialized as file references and generate skip diagnostics. Use BasicAnalyzerKind.OnDisk or BasicAnalyzerKind.None to avoid this.

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